555-24-8Relevant articles and documents
Chemical shifts of phenolic monomers in solution and implications for addition and self-condensation
Haupt, Robert A.,Renneckar, Scott
, p. 95 - 101 (2013/03/14)
Alkali metal counter-cations alter the electron density of phenolates in solution by electrostatic interactions. This change in electron density affects their reactivity toward formaldehyde, hydroxymethylphenols, and isocyanates during polymerization. The electronic perturbation of phenolic model compounds in the presence of alkali metal hydroxides was investigated with 13C and 1H nuclear magnetic resonance in polar solvents relative to non-ionic controls, altering the chemical shifts of the model compounds, thus indicating changes in electron density using the chemical shift as a proxy. These shifts were attributed to Coulombic electrostatic interactions of the counter-cation with the phenolate anion that correlated to hydrated ionic radius and solvent dielectric constants. The predicted relative reaction rates for formaldehyde addition based on electron density ranking from 13C nuclear magnetic resonance of the phenolic models was compared with the literature values. Predictions for condensation reactions of 2- and 4-hydroxymethylphenol from chemical shifts were consistent with published results. The results permit predictions for the reaction of phenolic compounds for the formation of thermosetting polymeric materials. Copyright
[2+2] and [2+4] type cycloadditions of isocyanates with ynolates
Shindo, Mitsuru,Harada, Akiko,Matsumoto, Kenji,Shishido, Kozo
, p. 39 - 43 (2007/10/03)
Ynolates react with isocyanates to give azetidine-2,4-diones via a [2+2] type cycloaddition. The [4+2] type cycloaddition proceeds in the reactions of vinyl isocyanates with ynolates to provide 2-pyridones.
Proton affinities and aggregation states of lithium alkoxides, phenolates, enolates, β-dicarbonyl enolates, carboxylates, and amidates in tetrahydrofuran
Arnett, Edward M.,Moe, Kevin D.
, p. 7288 - 7293 (2007/10/02)
The proton affinities of the title compounds are represented by their heats of deprotonation, ΔHdep, through reactions with lithium bis(trimethylsilyl)amide, LiHMDS, in tetrahydrofuran at 25°C. Aggregation numbers of the parent acid and of its lithium salt at a concentration of 0.10 M were obtained by vapor-pressure osmometry at 37°C. Lithium phenolates were also studied by conductivity at 25°C. ΔHdeps for 27 oxygen, nitrogen, and carbon acids of varied types correlate fairly well (R = 0.95) with their published pKas in dimethyl sulfoxide although their degrees of aggregation in THF vary from one to over seven. In some cases, the ΔHdep of an acid is strongly dependent on the concentration ratio of LiHMDS to that of the acid's lithium salt at the time of measurement. Aggregation numbers determined by VPO in this report agree with available published values obtained by previous workers using several techniques. There is no obvious relationship between the aggregation number of the lithium salt and the basicity of the corresponding anion as represented by ΔHdep. This observation along with independent evidence for equilibria between monomers, dimers, tetramers, etc. for a number of compounds indicate that there are only small differences between the relative stabilities of different aggregation states. Conductance data for lithium p-nitrophenolate were treated by Wooster analysis, the results of which suggest equilibria between ion triplets, ion pairs, and free ions in THF. The conductance of LiHMDS in this solvent is surprisingly high, and this property was used to demonstrate an interaction between LiHMDS and lithium o-tert-butylphenolate.
